The present invention relates in general to sluing gear arrangements and in particular to a new and useful sluing drive for excavators having a pivotable superstructure and a pivotable discharge boom.
Excavating or bulk handling machines are known which utilize sluing mechanisms that are driven by one or more drive motors. Such machines include discharge boom assemblies which are mounted on rotary supports that are coaxial with rotatable superstructures. The superstructures carry the rotary support as well as other equipment. Sluing drives of the rotary support and the superstructure are connected to each other so that the superstructure and discharge boom can be pivoted separately.
Such machines have the advantage that upon sluing the superstructure and the equipment, for example digging means supported in the superstructure, the discharger boom does not change its position. This facilitates the operation of the machine. On the other hand, the discharger boom can be slued independently of the superstructure. In prior art excavating or bulk handling machines, the respective sluing gears are positively engaged. This positive engagement can be provided only at a single location between the gear rim of the sluing gear of the discharger boom and the main sluing gear of the superstructure, which is disadvantageous. Upon a failure in this positive engagement due to a shaft fracture, tooth breakage, and the like, the discharger boom is no longer retained by the discharger sluing gear and may accidentally change its position due to wind pressure or tilt of the machine. When this happens the boom may hit other parts of the superstructure and destroy the machine.